CXCR4 and CD83 define human LZ and DZ B-cell populations. (A) Flow cytometric profile of day 10 mouse lymph node GCs and human tonsil GCs stained for markers CXCR4 and CD83. LZ and DZ gates and percentages are shown. Gating as shown in supplemental Figure 1A. (B-D) Each plot is representative of at least 4 independent experiments. Immunofluorescent staining of frozen tonsil (B-C) or paraffin-embedded reactive lymph node (D) samples showing the anatomic distribution of CXCR4 (B), CD86 (C), and CD83 (D) in human GCs. Light zones are defined by CD23 staining (green). Note that CD23 and CD86 staining appears to overlap in the LZ because of insufficient resolution of confocal microscopy to discern molecules expressed on juxtaposed membranes. The GC perimeter is defined in frozen and paraffin-embedded sections by counterstainings with IgD and DAPI, respectively (both in blue). Scale bars represent 100 μm. Histology data are representative of 2 independent experiments. Image acquisition parameters are described in “Microscopy.”